Spacer for reinforcing mesh for concrete pipe and the like



Oct. 14, 1969 R. A. SWENSON 3,471,986

SPACER FOR REINFORCING MESH FOR CONCRETE PIPE AND THE LIKE FiledOct. 2a.1966 FIGB. i FIG-4.

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I INVENTOR RICHARD A.SWENSON HIS ATTORN EYS United States Patent US. Cl.52-652 6 Claims ABSTRACT OF THE DISCLOSURE A snap-on spacer element forstructural reinforcing mesh formed from a flat band of spring type metalto have a hook at one end to receive a rod of the reinforcing mesh. Theother end of the member is formed in an S-shaped hook which can besnapped over a parallel rod of the mesh to firmly retain the spacerelement in position by the resilient force of the element. The centralportion of the spacer includes a shank portion extending substantiallyparallel to the reinforcing mesh and a V- shaped projection portionextending from the shank portion to space the mesh from a surface.

This invention relates to the manufacture of concrete pipe, and moreparticularly to devices for accurately loeating and positioningreinforcing material such as reinforcing mesh or fabric in molds forconcrete pipe.

In the manufacture of concrete pipe, wet concrete is poured into a moldhaving an annular cavity which imparts the proper shape and form to thefinished product. It is quite common to position in the mold before theconcrete is poured into it, a sleeve or cage of steel reinforcing meshwhich becomes embedded in the concrete and greatly strengthens theresulting pipe. It is well recognized in the art that the positioning ofthe reinforcing mesh with respect to the inner and outer surfaces of thewalls of the pipe is very important in producing strong pipe, that is,if the mesh is too close to or too far from either the inner or outersurface, the pipe is weakened and will be weakened further as thereinforcing decomposes due to inadequate concrete cover protection.Moreover, if the mesh is not located generally co-axially with respectto the center line of the pipe, the wall strength of the pipe will varyand thus the pipe will not give satisfactory service or meet standardsfor such pipe.

For the above reasons, various expedients have been proposed forpositioning the mesh in the mold or form so that when the concrete ispoured into the mold, the mesh will be retained in a predeterminedposition with respect to the inner and outer surfaces of the pipe. Amongthe expedients proposed are spacers welded to the mesh which projectoutwardly beyond the plane of the mesh to contact the mold and thusspace the mesh more or less uniformly with respect to the outer or innerwalls of the mold. This expedient is expensive because of the weldingoperations involved and, moreover, is not very satisfactory because ofthe tendency of the welding heat to warp and deform the spacers as wellas the mesh itself and to burn away some of the required meshreinforcement.

Another practice is to cut the mesh and bend portions out of the planeof the mesh to form spacing legs which contact the mold at variouspoints along the length and width of the mesh. This practice likewise isnot very satisfactory because unless the mesh is cut and bent quiteaccurately, the lengths of the legs vary and produce an inaccuratelocation of the mesh in the mold. Moreover, by cutting the mesh, itsoverall strength is reduced with the result that pipe containing suchmesh is either weaker or additional reinforcement is required tore-establish the strength of the mesh.

Another type of spacer is a bent hairpin-like hook which is hung over aportion of the mesh and bears against other ortions of the mesh to spacethe mesh from the wall of the mold. These spacer hooks, in practice, arenot very satisfactory because when the concrete is poured into the mold,which is usually in a vertical position, spacers sometimes are dislodgedand fall to the bottom of the mold so that the reinforcing mesh canshift and move relative to the walls of the pipe mold even to the extentthat portions of the mesh are exposed at the inner or outer surfaces ofthe pipe.

In accordance with the present invention, spacers are provided which areinexpensive to produce and can be attached securely and quickly to thereinforcing mesh so that they cannot be dislodged during pouring of theconcrete into the mold thereby assuring accurate spacing of the meshwith respect to the inner and outer walls of'the mold and properpositioning of the mesh in the concrete pipe to obtain maximum strength.

More particularly, in accordance with the present invention, the spacersmay be formed of a spring type metal having a hook at one end which canbe hooked over one of the bars, wires or rods of the reinforcing meshand a curved and hook-like opposite end which can be snapped overanother wire or rod of the mesh to securely retain the spacer inposition. A corrugation or projection is provided on the spacer whichserves to space the generally sleevelike reinforcing mesh from the wallof the mold by either engaging the inside or the outside of the moldthereby locating the mesh accurately with respect to both walls of thepipe mold. By providing a series of such spacers along the length andWidth of the mesh, little or no displacement of the mesh can occurduring the molding of the pipe, and also due to the strong retention ofthe spacers on the mesh, they are not dislodged by pouring the concreteand by tamping, vibrating or other operations involved in themanufacture of the pipe so that the reinforcing mesh cannot shift to aneccentric or canted position with respect to the inner and outersurfaces of the finished pipe and the walls of the mold.

For a better understanding of the present invention, reference may behad to the accompanying drawings, in which:

FIGURE 1 is a plan view of an annular mold for concrete pipeillustrating the positioning of a concrete reinforcing mesh or fabric inthe mold by means of spacers of the type embodying the presentinvention;

FIGURE 2 is a view in section taken on line 2-2 of FIGURE 1;

FIGURE 3 is a side elevational view of a spacer embodying the inventionapplied to a portion of concrete reinforcing mesh, shown in section;

FIGURE 4 is a sectional view taken on line 4-4 of FIGURE 3; and

FIGURE 5 is a side elevational view of a modification of the spacerapplied to a section of reinforcing mesh.

Referring to FIGURE 1, a typical pipe mold includes an inner, usuallyhollow cylindrical core 10 formed of any suitable material such as, forexample, steel, and an outer cylindrical mold member 11 formed ofsimilar material. The core and outer mold member can be split into oneor more parts to enable the removal of the pipe from the mold.

As indicated in FIGURE 1, it is common to reinforce concrete pipe withone or more layers or cages or sleeves 12 of concrete reinforcing meshcomprising longitudinal wires, bars or rods 13 welded to transversewires, bars or rods 14 to form a metallic mesh fabric, the spacing ofthe wires varying as the purpose demands. Thus, reinforcing mesh having2-, 3-, 4-inch or greater spacing of the wires or rods, and even unequalspacing of the vertical and transverse wires may be provided.

As indicated above, in order to provide concrete pipe of optimumstrength characteristics, it is essential to have the reinforcing meshspaced uniformly with respect to the outer or inner surfaces of thewalls of the finished pipe, the actual spacing depending upon thesection of the pipe, e.g., the thickness of the concrete wall of thepipe. To this end, and in accordance with the invention, spacers of thetype shown in FIGURES 3 to are provided. The spacers are formedpreferably of spring metal strip such as, for example, medium to highcarbon tempered steel strip. In practice, the strip may be about of aninch wide by about .050 of an inch thick. These dimensions can be variedso long as the spacer is of sulficient strength and resiliency for thepurpose. One end 15 of the spacer 16 (FIGURES 3 and 4) is bent intohook-like shape so that it can be hooked over one of the horizontallydisposed rods or Wires 14 of the mesh, for example. The opposite end 17of the strip is bent into a generally S-shaped formation so that it canbe forced over a parallel rod or wire 14 of the reinforcing mesh andsnapped into position and locked to the mesh by the springiness of thesnap spacer. Between the ends 15 and 17, the strip is bent to form agenerally V-shaped projection 18 of a height which determinees thespacing of the mesh 12 from the outer or inner wall 11 or of the pipemold. Thus, for example, in a typical snap spacer, the height of theV-shaped projection may be on the order of 1 inch or less to 2 inches ormore, depending upon the wall thickness of the finished pipe and thedesired location of the mesh in the pipe wall. The shape of the hook 17and the width of the strip will prevent the spacer from being deflectedor canted sideways by stresses thereon, thereby further assuring propercentering or positioning the mesh relative to the surfaces of theconcrete structure. The overall length of the spacer may be varied asthe purpose demands and it may be of such length that it merely spansthe spacing between two wires or rods of a 2-inch mesh, a 3-inch mesh ora 4-inch mesh or, as illustrated in FIGURES 3 and 4, the length may besuch as to span two meshes so that it can be used on, for example, a4-inch mesh or a 2-inch mesh. With a four inch spacer used with a 2-inchreinforcing mesh, as illustrated in FIGURES 3 and 4 the projection 18 isoffset nearer one of the ends of the spacer so that the intermediate rodor wire 14' bears against the back of a straight shank portion of thespacer, which thus gives it still additional supporting strength whenunder stress as the mesh is positioned in the mold. The spacer 26 shownin FIGURE 5 is similar to the spacer 16 but is of such length that itspans only one pair of bars or rods of the mesh 27. In this type of snapspacer, the projection can be spaced equidistant from the ends of thespacers.

The shape of the projection 18 is susceptible to modification, forexample, instead of being V-shaped the spacing projection 18 may beU-shaped, arcuate, or of other suitable form, so long as it projectssufficiently from the mesh toward the wall of the pipe mold to assuresubstantial concentricity of the sleeve or reinforcing mesh in thefinished pipe. However, a V-shaped projection is preferred for thereason that less material is required in the spacer and it resistsbetter any stresses tending to distort it or disengage it from the mesh.

Other variations and modifications of the spacer and the uses thereofare possible within the scope of the invention and accordingly, theforms of spacers illustrated in the drawings should not be considered aslimiting the invention defined in the following claims.

I claim:

1. A concrete reinforcing structure comprising a mesh of the type havinga series of uniformly spaced substantially parallel wires, and areleasable spacer for locating a point on the mesh in spaced apartrelation to a surface including a resilient member having a first hookformed at one end thereof receiving a wire of the mesh and a secondS-shaped hook at the other end thereof yieldably engaging a parallelwire of the mesh to releasably and firmly secure the member to the meshby the resilient reaction force between said S-shaped hook and theparallel wire, and a projection on said member for maintaining said meshin spaced relation to the surface.

2. The structure of claim 1 in which the distance between the first andsecond hooks is equal to a multiple of the distance between adjacentparallel wires of the mesh.

3. A concrete reinforcing structure comprising a mesh of the type havinga series of spaced substantially parallel wires, and a releasable spacerfor locating a point on the mesh in spaced apart relation to a surfaceincluding a resilient member having a first hook formed at one endthereof receiving a wire of the mesh, a second hook at the other endthereof yieldably engaging a parallel wire of the mesh to releasablysecure the member to the mesh, a projection on said member formaintaining said mesh in spaced relation to the surface, and a straightshank portion intermediate the projection and one of the ends andengaging at least a point of the surface of a parallel wire between thewires engaged by the first and second hooks.

4. A snap-on spacer for locating in spaced apart relation to a surfacestructural mesh including spaced wires, comprising a unitary member ofrelatively stiff, wide spring material having at one end thereoffirsthook means for receiving a wire of the reinforcing mesh and havingat the other end thereof an S-shaped hook including a concave surfacefor engaging the surface of the wire and a convex lip for guiding thehook over the surface of the wire, thereby to releasably secure thespacer to the wires of the mesh, and a projection on said memberextending normal to the mesh when the first and second hook means engagethe parallel wires and having a projection distance from the mesh equalto the desired spacing between the mesh and the surface.

5. A spacer as defined in claim 4, in which the concave surface of theS-shaped hook means is concave toward the other hook means to maintainthe member in longitudinal tension.

6. A snap-on spacer for locating structural reinforcing mesh in spacedapart relation to a surface, comprising a unitary member of flatrelatively stiff but resilient material having at one end thereof firsthook means for receiving a wire of the mesh and having at the other endthereof second S-shaped hook means to yieldably pass over a parallelwire of the mesh during attachment of the member to the mesh andthereafter firmly engage the parallel wire, said hook means being joinedby a relatively straight shank portion and a bent projecting portionextending outwardly from the mesh when the member is attached thereto.

References Cited UNITED STATES PATENTS 1,379,625 5/ 1921 Hartman.1,421,807 7/1922 Metzger 52-684 3,257,767 6/1966 Lassy 52-652 J. SPENCEROVERHOLSER, Primary Examiner JOHN S. BROWN, Assistant Examiner US. 01.x12. 25-118; 52-449, 414; 249-91

